xubuntu wrote: ↑Mon Mar 20, 2023 9:07 am
Xav,
Why were the numbers -33 +33 chosen? Strategic importance? Numeric importance? Or can we swap them with any number?
Xubuntu, just a question.
How long do you have a ZX81?
Anyone who has a ZX81 for longer time knows that a line on a full screen is 33 bytes (32 printpositions and a linefeed).
I have it like less than a year. Not used it more than 1 hour in total. I do my research on the emulator. It is a very interesting machine though. It has the "X" factor. My first computer was a 286. I am just 40, in my flowering age. Not ancient like you guys in here.
However, it seems to my tiny brain that it is not essential to keep the numbers as -33, 33. I presume that If numbers were -22, 22 for instance, the program would still work. Am I right?
xubuntu wrote: ↑Tue Mar 21, 2023 7:44 am
I have it like less than a year. Not used it more than 1 hour in total. I do my research on the emulator. It is a very interesting machine though. It has the "X" factor. My first computer was a 286. I am just 40, in my flowering age. Not ancient like you guys in here.
However, it seems to my tiny brain that it is not essential to keep the numbers as -33, 33. I presume that If numbers were -22, 22 for instance, the program would still work. Am I right?
You are both right and wrong. The ZX81 has a dinamic sized screen. in this game it is full size and then the step to go 1 line up or down is 33. when your screen would be size 21 columns your step would be 22.
We have now entered the Spring system. Standby alert! Summer approaching
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb.
Mister bleep, the D variable in the game is not pictured on the map. The P variable is what holds the location of the player on the map.
The D variable just checks if the P variable is oriented horizontically or vertically. Then the game checks the side pixels of the P variable to see if they are black (so there is a wall) or white (so the player can move towards that direction). And then if D is equal to -33 for instance, it sets the new D to 1 if there is no wall aside, or back to -33 if the player can't rotate because there is a wall.
I don't think the numbers here matter. D variable could rotate from -13 to 1 and it would still indicate the same thing.
But then again No... I am wrong. D matters indeed. Because sometimes the D is added to the P, which means that when the player TURNS.. the new P points map location based on the D... that is why we see poke (P+D)..
hmm.. that game is genius... the most clever game I ever saw in Basic.....
Last edited by xubuntu on Tue Mar 21, 2023 8:46 am, edited 2 times in total.
We have now entered the Spring system. Standby alert! Summer approaching
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb.